1. Field of the Invention
The present invention relates to an audio decoding method and apparatus, and more particularly, to an audio decoding method and apparatus wherein high quality audio signals can be obtained and output by reconstructing high frequency components thereof with less computation. The present application is based on Korean Patent Application No. 2002-75529, which is incorporated herein by reference.
2. Description of the Related Art
In general, a psychoacoustic model is used to compress audio data more efficiently in audio coding such that fewer bits are allocated to high frequency components inaudible to the human ear. In such a case, the compression rate is increased, but high frequency audio signals are lost. Due to the loss of high frequency audio signals, when the audio data are reproduced, the sound tone is changed, readability is lowered, and subdued or dull sounds are generated. Thus, a post-processing method for reconstructing the lost high frequency components for sound quality enhancement is required so as to fully reproduce the tone of an original sound and increase the readability of the audio signals.
The post-processing method for enhancing the sound quality of audio signals is described in connection with FIG. 1. Referring to FIG. 1, if encoded signals are input, they are separated into right and left channel signals and the separated signals are decoded, respectively, through a decoder 110. Then, high frequency components for the decoded right and left channel signals are reconstructed by first and second high frequency component generator units 120, 130, respectively.
However, since the right and left channel audio signals of most audio signals are generally similar to and highly redundant with each other, they are not individually encoded. Therefore, there is a problem in that the conventional post-processing method for separately reconstructing the right and left channel signals cannot efficiently utilize similarities between channel signals, and thus, computation time is unnecessarily increased.